Support `TextView#setTextAppearance` in layout DSL

[guersam]

Currently we don't have any shortcut for [void setTextAppearance(Context, Int)](https://developer.android.com/reference/android/widget/TextView.html#setTextAppearance(android.content.Context, int)) as it takes Context as one of args. Is there any way to support this by Scaloid DSL?

Because it refers to another attr, it's hard to be automatically converted from XML.

[pocorall]

Does the word 'support' you used means that providing DSL-style setter with implicit Context?

i.e. STextView.textAppearance_=(resid: Int)(implicit context:Context)

[guersam]

Unless the implicit parameter doesn't break a following method chain. I
said a bit vaguely because I haven't tried it yet.

[pocorall]

Method chaining works fine with an implicit parameter:

    class Foo {}
    class Bar {
      def something(a: Int)(implicit context: Foo): Bar = {
        println("a==" + a)
        this
      }

      def bar() = println("bar()")
    }
    implicit val foo = new Foo
    new Bar().something(3).bar()

Based on this issue, I imagined something like this:

If a setter has just two parameter and the type of the first parameter is Context, it is automatically converted to DSL-style setter with implicit context.

Could you try this?

[pocorall]

The last line does not be compiled.

    class Foo {}
    class Bar {
      def something(a: Int)(implicit context: Foo): Bar = {
        println("a==" + a)
        this
      }

      def something_=(a: Int)(implicit context: Foo) = something(a)

      def bar() = {
        println("bar()")
        this
      }
    }
    implicit val foo = new Foo
    val b = new Bar().something(3).bar()
    b.something = 9

yields the error value something is not a member of Bar

[pocorall]

Anyway, method chaining new Bar().something(3).bar() is proven to be valid. Could you manage to the automatic conversion issue above?

[guersam]

I'll look into it after first draft of new layout converter is done.
If you really want to use something_= as well, here's a solution:

class ValueWithContext[A] private (val value: A, val context: Context)
object ValueWithContext {
  implicit def apply[A](value: A)(implicit context: Context) =
    new ValueWithContext(value, context)
}

// ...
class Bar {
  // .. 
  def something_=(vwc: ValueWithContext[Int]) = something(vwc.value)(vwc.context)
//..

[guersam]

A brief confirmation in REPL:

scala> :paste
// Entering paste mode (ctrl-D to finish)

class C
class V[A](val v: A, val c: C)
object V {
  implicit def apply[A](v: A)(implicit c: C) = new V(v, c)
}

// Exiting paste mode, now interpreting.

warning: there were 1 feature warning(s); re-run with -feature for details
defined class C
defined class V
defined module V

scala> class B {
     |  var _a: Int = _
     |  def a = _a
     |  def a(v: Int)(implicit c: C) = { this._a = v; this }
     |  def a_=(v: V[Int]) = this.a(v.v)(v.c)
     | }
defined class B

scala> val b = new B
b: B = B@1ddf7713

scala> b.a = 1
<console>:14: error: value V is not a member of object $iw
       b.a = 1
             ^

scala> b.a(1)
<console>:15: error: could not find implicit value for parameter c: C
              b.a(1)
                 ^

scala> implicit val c = new C
c: C = C@494a8227

scala> b.a(1)
res5: B = B@1ddf7713

scala> b.a
res6: Int = 1

scala> b.a = 2
b.a: Int = 2

scala> b.a
res7: Int = 2 

[guersam]

The error message in line 14 looks somewhat ugly though.

[pocorall]

Good, looking forward the integration into Scaloid!